The present invention relates to a pressing machine that combines a plurality of modular press units together in each of which a C-form frame is adopted.
A pressing machine of the type described has been known that adopts a modular structure in which the press assembly is made up of a plurality of modular press units which are each built up and are interconnected to act as successive pressing stations of a given forming process.
Each of the press units so far employed in a pressing machine of modular structure comprises a bed, a plurality of uprights mounted to stand on the bed and a crown laid over the uprights. The press units thus taking each a portal structure have so far been used to build up primarily a progressive or a transfer press system.
The crown in each of the press units has installed therein a slide drive mechanism that may comprise a crank mechanism or a link mechanism, to which a slide is connected, e.g., at two or four points. Thus in each press unit, moving the slide vertically through the slide drive mechanism is designed to permit a work to be press formed between an upper die attached to the slide and a lower die mounted on a bolster.
In such conventional pressing machines of modular structure as described, inconveniences have been found to exist, however, e.g., because of a limitation in forming processes that can be adopted. Thus, since these press units are left independent of one another for different working stations with the slide and the bolster in one press unit being isolated from the slide and the bolster in another press unit, respectively, it has been impossible to attach and mount dies across these press units and then to adopt a forming process to form a work simultaneously in more than one press units.
Also, the use of a crank mechanism or a link mechanism for the slide drive mechanism does not allow the stroke distance of the slide to be altered as desired and hence has so far limited the machine""s maximum possible output. Also, the press unit being of portal structure in which uprights are mounted on the bed to stand at its four corners has been found inconvenient, e.g., in that the uprights hinder installing a work conveyer means, or impede performing a setup operation in changing the dies to make it time-consuming and of poor workability.
Further, connecting the slide to the slide drive mechanism at two or four points has required that the slide and the bed be stiff and large enough to prevent them from deforming under a pressing load acting on them. Not only has this made the pressing machine costly, but the pressing machine inconveniently becomes high in its total height so as to require a pit deep or a building high enough to accommodate it. A further inconvenience is that if different pressing loads are acting on these point areas, shut heights may result varying from point to point, which impair parallelism between the lower surface of the slide and the upper surface of the bolster, hence the inability to form with due precision.
With the view to avoiding or alleviating these inconveniences met by the conventional pressing machine of modular type, it is an object of the present invention to provide a pressing machine of modular type that enables a forming process to be performed using a die that extends across press units. It is also an object of the present invention to provide a pressing machine of modular type that is high in productivity and forming precision and yet that can be made inexpensively.
These and other objects which will become more readily apparent hereinafter are attained in accordance with the present invention in a first form of implementation thereof by a pressing machine for forming a work being progressively fed along a coil line, having a press assembly that comprises a plurality of modular press units connected from one to another in a direction in which the work is progressively fed, each of the press units including a C-form frame, a slide drive mechanism disposed in an upper part of the C-form frame and having in its drive source a servo motor means operable under NC (numerical control), and a slide adapted to be driven by the slide drive mechanism to move in a given movement pattern, the press units having their respective slides as aforesaid, at least some of the slides having at least one slide adapter attached thereto, the at least one slide adapter extending across the at least some of the slides as a whole.
The construction described above permits a die or dies to be attached to the slide adapter over an entire length thereof and thus provides a pressing machine of modular type with a substantial expansion in the freedom to form, including an added ability to form an elongate work. Also, rendering the drive sources for the slide drive mechanisms in the press units operable each individually under NC allows the shut heights for all the slides to be maintained constant if different forming loads are acting on the slides. Thus, even then, the parallelism between the upper surfaces of the beds and the lower surface of the adapter plate can be held always constant, and the forming surfaces of all the dies can easily be adjusted in a given height, thereby permitting a work to be formed with due precision.
Also, using a servo motor operated under NC for the drive source for the slide drive mechanism allows the slide movement to be set in any given pattern as desired. Since this also allows the forming rate to be raised for a work that can be formed in a short slide stroke length, a substantial enhancement of productivity and a significant reduction of energy consumption are achieved for such works. It is also made possible for the slide or the slide adapter plate to be lowered fast immediately before the die carried by the slide adapter plate comes in contact with the work and then to be slowed down. Such a slide motion pattern has the effect of reducing the noises and vibrations which are emitted when the die is touching the work.
In addition, adopting a C-form frame in each of the modular press units gives rise to the advantage that the press unit and hence the pressing machine can be reduced in size, thus permitting the machine to be installed without the need for a deep pit or a high housing as hitherto required and hence quite with economy. Using C-form frames also allows resulting press units to be combined with an expanded freedom. It is thus made possible to make a choice easily between constructing a coil line with a minimum number of such press units and building a large-scale coil line in accordance with a particular kind of products to be formed.
Moreover, being devoid of the uprights in each of the press units renders it possible to accomplish easily and swiftly a setup operation as needed in exchanging dies, or as required to install or to adjust a work transfer means.
In order to achieve the objects mentioned above, the present invention also provides in a second form of implementation thereof a pressing machine for forming a work being progressively fed along a coil line, having a press assembly that comprises a plurality of modular press units connected from one to another in a direction in which the work is progressively fed, each of the press units including a C-form frame, a slide drive mechanism disposed in an upper part of the C-form frame and having in its drive source a servo motor means operable under NC, and a slide adapted to be driven by the slide drive mechanism to move in a given movement pattern, the press units having their respective beds, the beds having at least one bolster mounted thereon, the at least one bolster extending across a length of the press assembly.
The construction described above permits using a particular die individually for each of the press units. Thus, requiring only a die that is worn down to be exchanged, a pressing machine is provided that is economical to operate and maintain compared with conventional machines that necessitate exchanging all the dies as a whole.
Also, using a servo motor operated under NC for the drive source for the slide drive mechanism allows the slide movement to be set in any given pattern as desired. Since this also allows the forming rate to be raised for a work that can be formed in a short slide stroke length, a substantial enhancement of productivity and a significant reduction of energy consumption are achieved for such works. It is also made possible for the slide or the slide adapter plate to be lowered fast immediately before the die carried by the slide adapter plate comes in contact with the work and then to be slowed down. Such a slide motion pattern has the effect of reducing the noises and vibrations which are emitted when the die is touching the work.
In addition, adopting a C-form frame in each of the modular press units gives rise to the advantage that the press unit and hence the pressing machine can be reduced in size, thus permitting the machine to be installed without the need for a deep pit or a high housing as hitherto required and hence quite with economy. Using C-form frames also allows resulting press units to be combined with an expanded freedom. It is thus made possible to make a choice easily between constructing a coil line with a minimum number of such press units and building a large-scale coil line in accordance with a particular kind of products to be formed.
Moreover, being devoid of the uprights in each of the press units renders it possible to accomplish easily and swiftly a setup operation as needed in exchanging dies, or as required to install or to adjust a work transfer means.
In either of the constructions provided by the first and second forms of implementation of the present invention described above, the press units may be connected from one to another by fastening the respective C-form frames of the adjacent press units together by fastening means for the press units as a whole.
The specific construction described above increases stiffness properties of the C-form frames and thereby reduces their tendency to open under a forming load. Achieving a due forming precision is therefore ensured.
In any of the generic and specific constructions described above, the pressing machine preferably has a first and a second press assembly each of which is constructed as defined therein, the first and second press assemblies being arranged with their fronts opposed to each other across a coil line, the front of the first press assembly being defined by the respective front faces of the press units of the first press assembly and the front of the second press assembly being defined by the respective front faces of the press units of the second press assembly, each pair of the respective press units of the first and second press assemblies opposed to each other being interconnected by fastening their respective beds and crowns by fastening means for the press units as a whole.
This specific construction almost eliminates a shortcoming of presses that adopt C-form frames, i.e., the C-form frame tending to open under a forming load, and thus serves to markedly enhance forming precision attainable. That specific construction which also doubles the transverse width of the press body makes the resulting pressing machine available to meet with a requirement to form a wider work.
In any of the specific and generic constructions mentioned before, the machine preferably has a first and a second press assembly each of which is constructed as defined therein, the first and second press assemblies being arranged with their fronts opposed zigzag to each other across a coil line, the front of the first press assembly being defined by the respective front faces of the press units of the first press assembly and the front of the second press assembly being defined by the respective front faces of the press units of second press assembly, each pair of the respective press units of the first and second press assemblies opposed zigzag to each other being interconnected by fastening their respective beds and crowns by fastening means for the press units as a whole.
This specific construction provides the pressing machine with an expanded capability of forming and a variation of forming pattern, including an added ability to form works of different shapes or configurations on a pair of working lines across the coil line, established in the machine and an ability to form works by removing stock across a pair of press units opposed obliquely to each other. That specific construction enables works of different types to be formed at the same time. Thus, by increasing the yield of material that can be formed, it serves to reduce the unit prices of formed products.
In any of the constructions of the invention so far described, the pressing machine preferably further comprises spacer means adapted to be interposed between the respective C-form frames of the adjacent press units as a whole to permit an entire length of the press assembly to be established as desired.
This specific construction permits increasing the entire length of the press body and thus allows a work longer in length to be formed. It also permits providing an idling station between the working stations and makes it possible to perform a multiple step operation, e.g., a six-step forming operation with four press units.
Alternatively or in addition in any of the generic or specific constructions mentioned above, the pressing machine preferably further comprises spacer means adapted to be interposed between the respective beds and between the respective crowns of the press units opposed to each other as a whole to permit a width of the first and second press assemblies in their transverse direction.
This specific construction that permits increasing the width of the press body in its transverse direction allows a work wider to be formed. That specific construction also permits works to be formed on two rows of working line established as coil lines in the pressing machine, and thus allows achieving an increased productivity.
In this connection, it is desirable that the spacer means be made adjustable in width.
This specific construction permits altering the pitch between adjacent working stations and/or the pitch between a working station and an idling station as desired.
In any of the constructions mentioned above, the press assembly preferably includes press units for draw forming, and an adapter plate attached to the slides of the press units for draw forming is made independent of an adapter plate attached to the slides of the press units not for draw forming.
This specific construction prevents a forming load in a draw forming operation from effecting on any other forming operation, and thus ensures achieving a due precision the process incorporates a draw forming step.
These and other features, objects and advantages of the invention will be more readily understood or apparent to those skilled in the art from a reading of the following detailed description of preferred forms of embodiment of the present invention as illustrated in the various drawing figures.